.....as are airlines scheduling ten departures over five minutes.... :ugh:

Indeed it is and the largest part of it as well but if every man and his dog want to fly to the same place through the same bit of airspace what do you expect? Slots need to be issued to keep the traffic to levels where we have some chance of staying sane.

I find that the seconds it takes to give the crew their slot whether they ask for it or not is far less time than it takes to deal with a flight that is either too early or worse, too late on a slot.